In letter, President Barack Obama thanks the American people for making him a "better man"

President Barack Obama published a thank-you note to the American people on his last full day in office, saying Americans not only made him a "better president" but also made him a "better man."

"Throughout these eight years, you have been the source of goodness, resilience, and hope from which I've pulled strength," the outgoing president wrote in the letter, published Thursday morning on Medium.

NEW: Pres. Obama writes a final thank you letter to Americans: "You made me a better President, and you made me a better man.

He brought up communities coming together to pull through economic hardship, mourn mass shootings and help wounded veterans and refugees.

Obama told Americans that, while he will soon reclaim his civilian status, he will still work to help make the country a better place, saying he'll "be right there with you every step of the way."

"And when the arc of progress seems slow, remember: America is not the project of any one person," Obama wrote. "The single most powerful word in our democracy is the word 'We.' 'We the People.' 'We shall overcome.'"

He ended his thank-you with the phrase that propelled him to the Oval Office in the first place.